a123's for my b-day present. SHORTED OUT!!

[istandalone]

i'm pretty pissed right now. i got a 36v dewalt pack for my bday. upon removing the brick of cells from the plastic housing, and severing the wires that attach it to the circuit board i somehow must have touched metal to metal. BIG SPARK! and almost welded my wire cutters together. does this mean that all 10 cells are now shot and useless? the cells didn't even get warm, but i suspect that i'm hosed now.

[Duke600]

I have done the same thing and a couple of the cells were bad. They are to darn sinsitive to shorting out. One reason I went back to lipos.

[istandalone]

did you short the pack as a whole, or just a few? the whole brick was still wired in series from the factory. so what should i do? separate each cell and charge/discharge each cell on it's own and see what the readings are? i should expect around 2300mah from each cell, right? what voltage should i expect each cell to be at without charging or discharging?
They are to darn sinsitive to shorting out. One reason I went back to lipos.

i'm not sure i get what you mean. lipos are just as sensitive to shorting out, it's just harder to do with only one red and one black wire on lipos. so you shorted your pack, and exactly how many turned up bad? please explain how you tested them. btw, thanks for your advise.

[istandalone]

i'm actually very very suprised. what i've done is charge and then discharge each cell separatley. i've only got three more to do, but so far all the cells are good. they're charging to 3.6v and the lowest capacity discharge has been 2079mah and the highest is 2143mah. these cells are rated for 2200mah, correct? even the cell that shorted is charging and discharging good. how is this possible? i thought a short circuit was the end of the line for any kind of cell, be it nicad lead or lithium. anyone got any ideas?

[istandalone]

so here's the final rundown. each and every cell in the pack (when i shorted it, they were still wired in 10s1p configuration) reads 3.6v when fully charged and each cell was discharged at the max my charger would allow for which is 4 amps. i'll list the mah removed from each cell: 2083; 2110; 2108; 2098; 2134; 2091; 2143; 2079; 2115; and 2099. how is this possible? is it maybe because it was such a small fraction of a second when live wires touched? maybe the "weld" spot on my wire cutters actually acted as a fuse and just burnt up? either way i'm very impressed and sold on a123's. if i'd have shorted my evo 30's, it'd have been PUFF!

[Cryofix]

I arc'ed my pack and it melted the outside of one of the tops of the can, charged it up and used it no problems.

In order to check a series cell like the 10S pack, use a volt meter and just put it on the tops and bottom of the cells, begin with the cell the ground comes from and work around, you will have to add te cell values though.

First cell should read 3.3 next 6.6, 9.9 etc

[rcboosted]

A123 packs are known to take a lot of abuse, isn't that why you picked them? Not sure why you're surprised. They'll be fine, go fly them.

[wlfk]

I've had 2 minor shorts whilst I was building my packs. You feel completely stupid afterwards - how hard can it be to avoid shorting a pack?! But truth is it's very easy to do.

Have a look at the site where you shorted and see whether it penetrates the casing of the cell. If not, then you'll probably be OK. As other posters have said, monitor the cell to see whether it's dropping voltage. If you check the voltage after a flight and after you've charged the cells and it's neither too low nor too high compared to the others, then the chances are the cell will be OK.

My shorts were minor-ish, but I haven't noticed any difference between the 2 packs I shorted and the others.

As a precaution I'd tend not to leave the packs anywhere they might start a fire - at least for a few days. They won't make a flameball like LiPos (there is a video on YouTube of somebody drilling a hole in one) but they might conceivably get hot if they shorted out internally.

K